Tetravalent tin(IV) bis-laurate; clear pale-yellow liquid; MW 631.6; hydrolysis-sensitive Lewis acid catalyst.

DBTDL — chemical name dibutyltin dilaurate, also written as dibutyltin di(dodecanoate) — is a tetravalent organotin compound with two n-butyl groups and two laurate (C₁₁H₂₃COO⁻) ligands bonded to the tin centre. Molecular formula C₃₂H₆₄O₄Sn, molecular weight 631.6 g/mol, density 1.05 g/cm³ at 20°C, refractive index 1.469. SEMITECH supplies DBTDL as a clear pale-yellow liquid at ≥97% active content, with tin assay 18.0–18.5% by ICP-OES, water content ≤0.1% by Karl Fischer, and APHA colour ≤100. The compound is soluble in nearly all organic solvents (toluene, xylene, IPA, MEK, esters) and miscible with silicone fluids, polyols, and most polyurethane prepolymers — it is insoluble in water and decomposes on prolonged contact with atmospheric moisture, forming inactive tin oxide hydrates and free lauric acid.

DBTDL is the highest-activity organotin catalyst in commercial use, and the reference benchmark against which all other condensation-cure silicone and polyurethane catalysts are compared. The bis-laurate ligand structure provides the optimal balance of Lewis acidity at the Sn centre (laurate carboxylates moderately donate electron density, leaving the tin sufficiently electrophilic for catalysis) and steric accessibility (laurate is bulky enough to suppress hydrolysis but small enough to allow substrate coordination). Shorter carboxylate analogues (DOTL — diacetate; T-12 — dineodecanoate) trade activity for handling characteristics; DBTDL remains the reference workhorse where peak activity is required.

Activates the silanol oxygen via Sn-O coordination, accelerates alkoxysilane attack and alcohol byproduct release.

In condensation-cure RTV silicones, DBTDL coordinates to the silanol oxygen of α,ω-dihydroxy-PDMS, polarising the Si-O-H bond and lowering the activation energy for nucleophilic attack by an alkoxy- or oxime-functional silane crosslinker. The reaction releases the alkoxide (methanol, ethanol) or oxime (methylethylketoxime) byproduct, regenerates the catalyst, and forms a new Si-O-Si crosslink. At a typical 0.1% loading in alkoxy-cure RTV-1, tack-free time at 23°C and 50% relative humidity is 30–60 minutes; full cure to 90% of ultimate properties takes 24–72 hours depending on section thickness (the rate-limiting step is moisture diffusion into the bulk, not the catalysed reaction itself).

• Loading 0.05–0.15% — long-pot-life RTV-1 sealants (overhead vertical applications, large bead extrusion)
• Loading 0.15–0.30% — standard alkoxy-cure RTV-1 and RTV-2 condensation rubbers; tack-free 30–60 min at 23°C/50% RH
• Loading 0.30–0.50% — fast-cure RTV-1 sealants for production-line bonding; possible at the cost of reduced shelf life
• Loading 0.01–0.10% — polyurethane gel-time control (1K and 2K systems)

In polyurethane systems, DBTDL accelerates the urethane (NCO + OH) and trimerisation (NCO + NCO) reactions selectively over the urea (NCO + H₂O) reaction — making it the standard gel-time catalyst for cast PU elastomers, RIM polyurethane, and alkyd transesterification. DBTDL poisons platinum addition-cure systems even at ppm-level cross-contamination; storage and metering equipment dedicated to platinum-cured silicone must never have contacted DBTDL.

Alkoxy/oxime RTV-1 sealants, RTV-2 mould rubber, PU foam delay catalyst, alkyd transesterification.

RTV-1 alkoxy-cure sealants are the largest application — neutral-cure construction sealants for glazing, sanitary, and industrial bonding. DBTDL at 0.10–0.20% paired with methyltrimethoxysilane (MTMS) crosslinker and α,ω-dihydroxy-PDMS gives a 25–40 min tack-free time, 7-day full cure, and elongation at break of 400–600%. RTV-1 oxime-cure sealants use the same DBTDL loading paired with methyltris(methylethylketoximino)silane and tolerate slightly higher catalyst loading (0.15–0.30%) to compensate for oxime’s slower release kinetics. RTV-2 condensation-cure mould rubbers (dental impression, prototype tooling, candle moulds) typically use 0.15–0.50% DBTDL in a two-part formulation with TEOS or ethyl-silicate-40 as the tetra-functional crosslinker.

Polyurethane elastomer cast moulding uses DBTDL at 0.01–0.10% in the polyol component to control gel-time. PU rigid foam uses DBTDL at 0.02–0.08% as a co-catalyst alongside an amine blowing catalyst, providing a 2–6 second delay before gel set. Alkyd resin synthesis and ester transesterification at 180–230°C uses DBTDL at 0.05–0.20% on resin solids — the higher temperature accelerates the inherently slow ester interchange while maintaining sufficient catalyst activity. Coating crosslinking in 1K alkyd-melamine and 2K alkyd-isocyanate systems uses 0.05–0.15% DBTDL to balance pot-life with cure-on-demand performance.

CoA on every shipment, 25 kg HDPE under nitrogen blanket, 12-month shelf life sealed, 2–4 week ex-China lead time.

SEMITECH issues a Certificate of Analysis on every batch with: tin assay (ICP-OES, target 18.0–18.5%), active content (titration vs. potassium iodate, target ≥97%), water content (Karl Fischer, target ≤0.1%), APHA colour (target ≤100), and refractive index. Standard packing is 25 kg HDPE jerrycans under nitrogen blanket; 200 kg lined steel drums available for bulk orders. MOQ is 25 kg per grade. Lead time ex-Zhejiang is 1–2 weeks to Asia gateway ports, 4–6 weeks to Rotterdam / Hamburg / Houston after sea freight transit. Air freight is available for laboratory and qualification quantities (1–5 kg), shipping within 5 working days of CoA approval.

Storage discipline matters: DBTDL hydrolyses on prolonged contact with atmospheric moisture, forming inactive tin oxide hydrates and free lauric acid that reduce catalytic activity and cloud the liquid. Sealed, original packaging stored below 25°C has a 12-month shelf life from manufacture; opened drums should be re-sealed under nitrogen and consumed within 60 days for consistent activity. Store away from strong oxidisers, acids, and bases. REACH and regulatory note: DBTDL is REACH-registered for industrial use; the 2010 Annex XVII restrictions on organotins target articles in skin- or food-contact (gloves, footwear, food packaging), not industrial silicone or polyurethane catalysts. SEMITECH issues a REACH compliance statement on every shipment. For consumer-facing skin-contact silicone applications (medical, dental, cosmetic), specify T-9 stannous octoate or shift to platinum addition-cure.

DBTDL is the reference tin catalyst — highest-activity organotin in commercial use, specified at 0.05–0.5% in alkoxy-cure RTV-1 sealants, RTV-2 mould rubber, and 0.01–0.10% in polyurethane elastomer systems. CoA on every shipment, 25 kg MOQ, 2–4 week ex-China lead time. Avoid all cross-contamination with platinum-cured silicone production lines.

SEMITECH stocked grade; CoA per batch.